Teff Eragrostis Tef Production Constraints On Vertisols in Ethiopia Farmers Perceptions and Evaluation of Low Soil Zinc As Yield Limiting Factor
Teff Eragrostis Tef Production Constraints On Vertisols in Ethiopia Farmers Perceptions and Evaluation of Low Soil Zinc As Yield Limiting Factor
Teff Eragrostis Tef Production Constraints On Vertisols in Ethiopia Farmers Perceptions and Evaluation of Low Soil Zinc As Yield Limiting Factor
To cite this article: Bereket Haileselassie, Tjeerd-Jan Stomph & Ellis Hoffland (2011) Teff
(Eragrostis tef) production constraints on Vertisols in Ethiopia: farmers' perceptions and
evaluation of low soil zinc as yield-limiting factor, Soil Science and Plant Nutrition, 57:4,
587-596, DOI: 10.1080/00380768.2011.593482
ORIGINAL ARTICLE
Abstract
Teff (Eragrostis tef (Zucc.) Trotter) is a major food crop in Ethiopia and Eritrea. It is well adapted to
Vertisols. Yields are low (around 1000 kg ha1) despite fertilization with urea and diammonium phosphate.
The objectives of this study were to understand farmers’ perception on teff production constraints and to
evaluate on-farm yield response of teff to zinc (Zn) fertilization. We conducted a farm survey and a
participatory fertilization experiment in three teff-based sites (peasant associations) on Vertisols in the mid
highland and lowland agroecological zones in Ethiopia. Per site 10 farmers participated in the survey and
on-farm experiment. Poor soil fertility in the mid highland and moisture deficit in the lowland agroecological
zones were mentioned by farmers as major teff production constraints, respectively. On-farm application of
Zn fertilizer at a rate of 8 kg Zn ha1 increased teff grain and straw yields by 14% and 15% on average,
respectively, which could be economically profitable. Not all plots showed a positive response, however,
indicating the necessity for enhanced insight in indicators for soil Zn bioavailability as a yield-limiting factor.
Our study indicates the importance of Zn in teff production on Vertisols. We propose further research on
management options to prepare for effective interventions based on the farm survey and on-farm experiment.
Key words: Eragrostis tef (Zucc.) Trotter, farmers’ perception, participatory research, Vertisol, zinc.
Site
Ude Hatsebo Selam Bikalisi
5.9 106 ha is in use by farming systems in which teff is Zinc, being a micronutrient for plants, animals and
an important crop (Bull 1988). Vertisols are dark, humans, would not only be relevant as a yield-limiting
montmorillonite-rich clay soils with characteristic shrink- factor, but also in relation to quality of food and feed.
ing and swelling properties. They have high clay content Zinc deficiency is widespread in Ethiopia’s human
(430% to at least 50 cm depth from the surface) and (Umeta et al. 2000; Hotz and Brown 2001; Umeta
when dry they show cracks of at least 1 cm wide et al. 2003) and cattle (Khalili et al. 1993) populations
and 50 cm deep (FAO 2000). They have high calcium that depend on teff grain and straw, respectively, as
and magnesium contents. major source of Zn. Teff Zn concentration has been
Nitrogen (N) and phosphorus (P) fertilizers are the reported to be low (Umeta et al. 2005). This could be
major soil fertility management practices applied by partly due to low soil Zn supply.
Ethiopian smallholder farmers growing teff on Vertisols. Information on farmers’ soil fertility management on
These fertilizers were introduced in 1967 following four Vertisols and their perceptions on production constraints
years of trials carried out by the government, with the of teff is limited. In this study we describe teff farming
assistance from the Food and Agriculture Organization’s systems on Vertisols in what has been classified as mid-
(FAO’s) Freedom from Hunger Campaign (FAO 1995). highland and lowland agroecological zones (Anonymous
Continuous application of N and P fertilizers without 2000) and evaluate Zn as possible growth-limiting
due consideration of other nutrients may have led to factor. To design future interventions we interviewed
deficiencies of e.g. potassium (Astatke et al. 2004) or zinc farmers to understand their perceptions on teff produc-
(Zn). It is suspected indeed that cereals’ response to N tion constraints and soil fertility management, and we
and P fertilization is declining on central mid to high performed a participatory on-farm Zn fertilization
altitude Vertisols (T. Mamo, Ministry of Agriculture and experiment.
Rural Development of Ethiopia, February 2008, personal
communication) indicating factors other than N and P MATERIALS AND METHODS
might potentially be growth-limiting.
Zinc could possibly be a yield-limiting factor on Site description
Vertisols (Dang et al. 1993; Ahumada et al. 1997; A farming system survey and an on-farm experiment
Rupa and Tomar 1999; Sharma et al. 2006). It can be were conducted in northern and central Ethiopia in
adsorbed to clay minerals, metal(hydr)oxides and 2008. The sites were selected upon advice of Debrezeit,
organic matter, specifically at high pH (Catlett et al. Axum and Alamata Agricultural Research Center
2002; Gao et al. 2010). In addition, Zn deficiency may Managers and Extension Office Heads at district level.
have a soil physical cause, related to the limited plant They suggested three peasant associations (sites) in teff
rootability of Vertisols or to low transport towards the growing areas where Vertisols are the dominant soil type.
root due to drought. Contrasting information is available The three selected sites differ in management practices
on the Zn status of Ethiopian Vertisols: Syers et al. and are located in the sub-moist mid-highland (Ude and
(2001) reported that Zn deficiency can be common in Hatsebo) and in the hot to warm lowland (Selam
Vertisols, Desta (1983) reported considerable variation Bikalisi) agroecological zones of Ethiopia (Anonymous
in micronutrient contents in soils in Ethiopia, Itanna 2000) (Table 1; Fig. 1). Hatsebo is not located in a main
(1996) reported low availability of Zn on Vertisols and Vertisol area (Fig. 1), but the farmers’ plots were on
according to Haque et al. (2000) the decision on small Vertisol pockets (Gebretsadikan et al. 2009)
(in)sufficiency depended on the extractant used. characterized by a high clay content and visible cracks
Zinc limits teff yield on Vertisols 589
(a)
300
250
200
150
100
50
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
(b) 300
Evapotranspiration (mm/month)
250
Monthly Rainfall and
200
150
100
50
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
(c)
300
250
200
150
100
50
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Time (month)
Figure 2 Average monthly rainfall (solid lines and squares), actual monthly rainfall in 2008 (bars) and estimated potential
evapotranspiration (dashed lines and triangles) for (a) Ude, (b) Hatsebo, and (c) Selam Bikalisi. Arrows indicate teff sowing (solid)
and harvest (dashed) in 2008.
livestock, crop residue utilization, crop rotation, possible standing at maturity. Estimations for area, urea and
crop rotation patterns, teff production constraints on DAP rates were based on the assumption that an oxen
their individual farm, characteristics of teff fields on plough day is equivalent to a quarter of a hectare land.
Vertisols in relation to fertility status and production For those who applied manure or compost, application
objectives and soil fertility management, and gave their rates were estimated from the farmers’ indication on the
opinion on the effects of the application of Zn fertilizer weight and number of bags applied per unit area.
on their plots. The farmers assessed the yield of the The group discussions mainly focused on production
Zn-fertilized and control plots while the crop was constraints and were moderated by facilitators from the
Zinc limits teff yield on Vertisols 591
Table 2 Soil properties of teff fields on Vertisols from the Farmers in Ude and Hatsebo were well aware of the
participating farmers importance of crop rotation to replenish soil fertility and
skillfully used this option. They choose the crop to be
Site
grown in rotation depending on rainfall (total amount
Soil parameters Ude Hatsebo Selam Bikalisi and distribution), soil type, market demand for the
legumes, expenditures such as loan and ceremonial as
pHwater (1:2.5) 6.8 0.1 7.8 0.1 8.0 0.1
Organic carbon (%) 1.3 0.1 0.8 0.0 1.2 0.1 well as the need to meet their food and livestock feed
P-Olsen (mg kg1) 12 2 11 2 61 requirements. Farmers prefer to grow chick pea and grass
DTPA-Zn (mg kg1) 0.92 0.07 0.59 0.02 0.54 0.08 pea as leguminous rotation crops and wheat as cereal
Clay (%) 57 1 58 1 41 1 rotation crop in both sites and in addition fenugreek in
Data represent means standard error (n ¼ 10). Hatsebo in rotation crop with teff on Vertisols. The
P-Olsen, available phosphorous using procedure by Olsen et al. (1954). leguminous rotation crops are usually planted towards
DTPA-Zn, Zinc (Zn) determined by diethylene triamine pentaacetate
extraction (Lindsay and Novell, 1978).
the end of August and partly grow on residual moisture.
Farmers in Ude and Hatsebo reduce their N fertilizer rate
for teff after leguminous crops, mostly for one year.
Farmers in Selam Bikalisi are not practicing crop
development agents and the research centers. The pro-
rotation. The main reason is traditional land allocation
duction constraints of teff were listed and ranked. While
to teff and sorghum, based on seasonal soil moisture
comparing the teff production constraints (two at a
conditions and soil fertility: relatively fertile lands
time), there was sometimes a debate before consensus
receiving seasonal floods from upstream are allocated
was reached.
to sorghum.
Farmers in all three sites carry crop residues away from
Data analysis their field. The aftermath is grazed by their animals. The
Both the quantitative and qualitative data from the major uses of crop residues are livestock feed, sale and
individual interviews and soil were analyzed using SPSS construction purposes. Farmers in Hatsebo and Selam
15.0 for Windows. Grain and straw yield data from the Bikalisi take part of their straw to the nearby markets of
on-farm Zn fertilization experiment were analyzed con- Axum and Alamata, respectively, where it is sold to feed
sidering site and Zn application rate as fixed effects, and urban livestock. Farmers in Ude sell part of their teff
farmers and their interaction with the fixed effects as straw to wholesalers who in turn sell the crop residue for
random effects. The variance components and their urban cattle fattening and dairy farms in the nearby
maximum standard errors of difference were generated towns of Debrezeit and Nazreit. Some of the crop residue
with GenStat 12.1 using the linear mixed models is sold in towns bordering Djibouti and Somalia. Crop
(REML) procedure. residue, especially of teff, is also used locally for
plastering after mixing with clay, and as manure fuel
cakes in all three sites. Rare farmers in Hatsebo use crop
RESULTS residues to make compost particularly from the remains
of livestock feed. Farmers in Selam Bikalisi use crop
Soil properties of the farmers’ fields on residue of sorghum for roofing and fuel. Here, sorghum
Vertisols stumps are also an important source of fuel for both the
Seven, ten and nine out of ten farmers’ fields on Vertisols rural and nearby urban dwellers.
were low in soil Zn (DTPA-Zn51.0 mg kg1) in Ude, The average farm size of teff fields on Vertisols and
Hatsebo and Selam Bikalisi, respectively. Mean livestock holding were higher in Ude than Hatsebo and
DTPA-Zn was low in all three sites (Table 2). Mean Selam Bikalisi sites (Table 3). In all sites, the average
soil pH varied from neutral to moderately alkaline. operated land of the farmers involved in the study in
The mean soil P status was high (P-Olsen410 mg kg1) 2008 was greater than the average owned landholding.
in Ude and Hatsebo and low (P-Olsen510 mg kg1) in
Selam Bikalisi. The mean soil organic carbon content was
Farmers’ perception on teff production
low (52%) in all sites.
constraints
At the first individual interview, before any hint to Zn as
Farming systems of the study sites a potential yield-limiting factor was made, poor soil
The major farming system was a mixed cereal/ fertility (Ude and Hatsebo) and moisture deficit (Selam
legumes-livestock system in Ude and Hatsebo and a Bikalisi) were mentioned among the three major
mixed cereal-livestock system in Selam Bikalisi (Table 3). constraints of teff production by all participating
592 B. Haileselassie et al.
Table 3 Summary description of farming systems as provided by the participating farmers at the three sites (n ¼ 10 per site)
Site
Descriptor
Ude Hatsebo Selam Bikalisi
Farming system Cereal/legume-livestock Cereal/legume-livestock Sorghum/
teff-livestock
Major crops Teff, wheat, chickpea, faba bean, Teff, wheat, barley, chickpea, Sorghum and
grass pea and lentil faba bean, grass pea, fenu- teff
greek, field pea and lentil
Major livestock Cattle, sheep, goat and donkey Cattle, sheep, goat and donkey Cattle, goat,
sheep and
donkey
Crop rotation Yes Yes No
Rotation pattern on Vertisols Year 1: Chickpea or grass pea Year 1: Chickpea or fenugreek or No
Year 2: Teff or wheat grass pea
Year 2: Teff or wheat
Rotation pattern on others soils Year 1: Faba bean or lentil Year 1: Faba bean or lentil or No
Year 2: Teff or wheat field pea
Year 2: Teff or wheat or barley
Crop residue removal Yes Yes Yes
Average own land holding (ha) 2.3 0.2 1.1 0.2 0.8 0.1
Average operated land 2008y (ha) 3.7 0.4 1.7 0.2 1.6 0.2
Average plot size of teff fields on 0.74 0.10 0.38 0.06 0.40 0.05
Vertisols 2008 (ha)
Average livestock holding, TLUz 8.5 1.0 3.4 0.6 3.6 0.8
yOwn plus rented or shared land.
zTropical livestock unit.
10 Ude
Hatsebo
9
Selam Bikalisi
constraint among the top three
Number of farmers mentioning
0
Poor soil High cost Pests Weeds Moisture Rains Water Lack of Labour in
fertility of deficit during logging draught peak
fertilizers ripening power seasons
Teff production constraint
Figure 3 Initial individual farmers’ identification of teff production constraints at the three investigated sites.
farmers (Fig. 3). In Ude and Hatsebo, the high cost of the past. Farmers tried to put this into words by
fertilizers ranked second. expressing the feeling that their land ‘‘is getting old’’.
In the group discussions organized per site after the Zn High cost of fertilizer was ranked as the second most
fertilizer experiment, poor soil fertility as constraint was important constraint in both sites. Weeds in Ude and
again ranked first both in Ude and Hatsebo. Farmers in pests in Hatsebo were ranked as third most important
both sites noticed that the yield response to urea and constraints. The results were almost identical to the
DAP application was less than they remembered from initial individual interviews as reported in Fig. 3.
Zinc limits teff yield on Vertisols 593
Table 4 Classification of the different teff fields on Vertisols Table 5 Farmers’ soil fertility management to teff fields on
during the 2008 cropping season as provided by the 10 Vertisols during the 2008 cropping season
participating farmers per site
Sitey
Sitey
Selam
Selam Type Ude (28) Hatsebo (18) Bikalisi (21)
Ude Hatsebo Bikalisi
Plot characteristics Class (28) (18) (21) Urea 73 4 (28) 86 10 (18) 0
DAPz 101 8 (28) 82 11 (18) 0
Soil fertility Unfertile 0 7 1 Compost 930 (1) 2000 (3) 1000 (1)
Medium 3 3 9 Manure 0 2000 (1) 1160 275 (6)
Fertile 25 8 11
Data (in kg ha1) represent means standard error.
Production Market 23 6 1
yFigures in parentheses indicate the number of teff fields evaluated.
objective Home consumption 2 8 9 zDiammonium phosphate (46% P2O5).
Both purposes 3 4 11
yFigures in parentheses indicate the number of teff fields evaluated.
Table 6 Main effects of zinc fertilizer and site on grain and
straw yields of teff studied on 10 farmers’ Vertisol fields per site
Table 7 Matrix showing yield effects for both grain and straw half of the plots (Table 7) despite the absence of any
of the application of 8 kg zinc (Zn) ha1 to teff plots in a history in urea and DAP fertilization that could have
participatory field experiment on 10 farmers fields each in three resulted in depletion of the soil from Zn, and even
sites comparing measured effects and effects as indicated by
farmers on the basis of visual inspection prior to actual though 2008 was considered as a relatively dry year
harvesting (Fig. 2). This could mean that Zn bioavailability is
inherently low in these Vertisols which is in line with
Indicated by farmers previous case studies from other Vertisol areas in the
Measured Positive No effect Negative world (Dang et al. 1993; Ahumada et al. 1997; Rupa and
Tomar 1999; Sharma et al. 2006). Consequently, also
Grain Positivey 9 3 2 other crops grown on these soils are at risk of Zn
No effect 10 3 3
deficiency, even at low N and P fertilizer rates.
Negativey 0 0 0
Straw Positivey 9 2 2 Average yield increases of 239 kg ha1 grain and
No effect 10 4 2 594 kg ha1 straw were recorded as a response to
Negativey 1 0 0 8 kg ha1 Zn fertilization (Table 6). Taking into account
yMore than 198 kg ha1 and 523 kg ha1 difference for grain and straw,
the local market prices of teff grain [700—1000 US dollars
respectively, between the Zn-fertilized and control plot (i.e. 2 standard (USD) ton1; Berhe 2009] and teff straw [49—150 USD
error of the differences of the treatment by location interaction effect at the ton1, as converted from local currency data provided by
same level of location in the Zn fertilization experiment).
Gebremedhin et al. (2009)], the additional production
would mean an additional income of 167 to 239 USD
farmers’ conditions. The on-farm experiments showed a ha1 from grain and of 29 to 89 USD ha1 from straw.
significant average yield increase upon Zn fertilization at The current price of Zn sulphate (heptahydrate, 21%
all three sites investigated (Table 6) and no interaction fertilizer grade) is 520 USD ton1 (cost, insurance and
between the Zn application and location. At two of the freight) at the ports in Djibouti or Sudan [W. Chen,
three sites farmers indicated poor soil fertility as a major Liuzhou Glory Zinc Minmetchem Co., Ltd. (Guangxi,
production constraint, both prior to and after the P.R. China), April 2010, personal Communication],
experiments. This offers excellent perspectives for inter- which for other inputs is roughly half of the farm gate
ventions that may not only lead to increased crop price in Ethiopia (Jayne et al. 2003). This would indicate
production, but also to improved quality of a major an average benefit/cost ratio for Zn fertilization between
staple food and feed for populations at risk of Zn 5:1 and 9:1, costs for application not included. This is a
deficiency. ratio generally considered attractive for market-oriented
Farmers’ perception in Ude and Hatsebo on poor soil farmers, who are the majority among the participants
fertility as the major teff production constraint (Fig. 3) (Table 4). Agronomical optimization of the ratios of N/P/
corresponded well with the results of our soil analyses Zn fertilizer could lead to a reduction of N and P fertilizer
and the results of the on-farm experiment. The soil rates in favor of Zn, which would further improve the
organic carbon content was low (Table 2), probably cost/benefit ratio of Zn fertilizer application.
because of the continuous and total removal of residues There was a fair correspondence between observed
from all crops in the rotation. The mean soil P status was positive yield effects on teff plots and the farmers’
high after long-term application of considerable amounts assessment (Table 7). There were, however, also ample
of DAP (Table 5). The mean soil Zn status, however, was false positive assessments of the Zn fertilizer effect on
low (Table 2) and teff grain and straw yields increased grain and straw yield. On two or three of the plots
significantly upon Zn fertilization (Table 6). Farmers’ appreciation for grain and straw yield, respectively, were
perceptions on poor soil fertility and their statements that opposite to measured effects. This implies that simple
their land ‘‘is getting old,’’ despite application of urea demonstration plots may not be enough to inform
and DAP, may therefore be related to depletion of their farmers about effects especially as false positive assess-
Vertisols from bioavailable Zn. We cannot exclude, ment would imply an additional financial risk to farmers.
however, that other nutrients may be depleted and have It should be noted that the participating farmers are
become yield-limiting as well. Additional trials would be probably not representing the majority of subsistence teff
needed to find out. growers in the studied areas. They were selected because
Regardless of the Zn fertilizer application, grain and they are relatively well exposed to extension services and
straw yields of teff were lowest in Selam Bikalisi. This is in conjunction their yields are relatively high. Further
probably related to the lower availability of P (Table 2), research and intervention strategies should not only
water (Fig. 2) and N due to the absence of legumes in the focus on this category of farmers but consider how to
rotation (Table 3). Yet, there was an average increase in scale out by involving other teff growers to learn from
yield upon Zn fertilization and a positive response on these potential early adopters.
Zinc limits teff yield on Vertisols 595
Not all plots showed a positive yield response to Zn Anonymous 2010a: Agricultural Sample Survey 2009/2010:
fertilization (Table 7). One plot showed a negative straw Report on Farm Management Practices, Statistical Bulletin
yield response, while on roughly half the plots no yield 468, Volume III, p. 15. http://www.csa.gov.et/survey/
effect was observed. The possible reasons could be Agricultural_Sample_Survery (January, 2011).
Anonymous 2010b: Agricultural Sample Survey 2009/2010:
variation in actual Zn limitation related to variation in
Report on Crop and Livetock Product Utilization,
bioavailability, interference with other yield-limiting
Statistical Bulletin 468, Volume VII, p. 17. http://www.
factor(s) or/and variation in handling and management csa.gov.et/survey/Agricultural_Sample_Survery (January,
of the experimental plots by the farmers. This implies 2011).
that blanket recommendations are bound to lead to Astatke A, Mamo T, Peden D, Diedhiou M 2004: Partcipatory
disappointments and these are thus inappropriate. on-farm conservation tillage trails in the Ethiopian high-
Additional insight in predictors of success of Zn fertil- land vertisols: the impact of potassium application on crop
ization that are plot specific should be sought to support yields. Exp. Agric., 40, 369–379.
possible introduction of Zn fertilization practices, in Berhe T 2009: Recent Development in Teff, Ethiopia’s
addition to verification studies over years and more Most Important Cereal and Gift to the World. http://
www.slideshare.net (December, 2010).
locations.
Blokhuis WA 1982: Morphology and genesis of Vertisols:
We also suggest further research on optimum N, P and
Vertisols and rice soils of the tropics, Transactions of the
Zn utilization including options such as seed coating/ 12th International Congress of Soil Science, pp 23—47,
priming and use of Zn-enriched fertilizers in sites similar International Society of Soil Science, New Delhi.
to Ude and Hatsebo. In Selam Bikalisi-like sites, with low Bull TA 1988: Agroecological Assessment of Ethiopian
soil fertility and current levels of manure and fertilizer Vertisols: Management of Vertisols in Sub-Saharan
application to teff fields (Table 5), integrated organic and Africa. ILCA, Addis Ababa, Ethiopia. http://www.
inorganic soil fertility management could be an entry fao.org/wairdocs/ILRI/x5493E/x5493e07.htm (January,
point for further research. 2011).
Catlett KM, Heil DM, Lindsay WL, Ebinger MH 2002: Soil
chemical properties controlling zinc2þ activity of 18
Colorado soils. Soil Sci. Soc. Am. J., 66, 1182–1189.
ACKNOWLEDGMENTS D’Andrea AC 2008: T’ef (Eragrostis tef) in ancient agricultural
systems of Highland Ethiopia. Econ. Bot., 62, 547–566.
The authors are grateful to the Debrezeit, Axum and
Dang YP, Dalal RC, Edwards DG, Tiller KG 1993:
Alamata Agricultural Research Centers and Extension
Understanding zinc reactions in vertisols to predict zinc
Offices, participant farmers and development agents responses by wheat. Plant Soil, 155/156, 247–250.
in Ude, Hatsebo and Selam Bikalisi, the Mekelle Soil Day PR 1965: Particle fractionation and particle-size analysis.
Laboratory Staff and Yirgalem Weldegebriel from In Method of Soil Analysis Part I, Ed. CA Black,
Ezana Mining PLC for their support. The authors pp 545—567, American Society of Agronomy,
thank Professor Dr Oene Oenema (WU) and Professor Madison, WI.
Dr Tekalign Mamo (Ministry of Agricultural and Debele B 1985: The Vertisols of Ethiopia: their properties,
Rural Development, Addis Ababa) for their construc- classification, and management. Fifth meeting of the East
tive ideas. The authors would like to thank Dr Alfred African sub-committee for soil correlation and land
Hartemink (ISRIC-World Soil Information) for sup- evaluation held in Wad medani, Sudan, 5—10 December
plying digital soil data and Dr Arnaud Temme (WU) 1983. In: World Soil Resources Report No. 56, pp. 31—54.
for making the map with the study sites. This study Food and Agricultural Organization, Rome.
Desta B 1983: Micronutrient status of some Ethiopian soils,
was funded by the Wageningen University sandwich
IAR Soil Science Bulletin No. 4, p 43, Institute of
PhD and INREF ‘‘From Natural Resources to Healthy
Agricultural Research, Addis Ababa.
People’’ programs and the Tigray Agricultural
Efrem B 2001: Performance of some cereals under drained
Research Institute. Vertisols in the Ethiopian highland. In Advances in
Vertisol Management in Ethiopian Highlands, Eds
REFERENCES D Paulos, D Asgelil, Z Asfaw, A Gezahegn, K Abebe,
pp 151—157, Ethiopian Agricultural Research
Ahumada TI, Bustamanate A, Schalcha EB 1997: Zinc speci- Organization, Addis Ababa.
ation in phosphate-affected soils. Comm. Soil Sci. Plant Food and Agricultural Organization (FAO) 1987: Master Land
Anal., 28, 989–995. Use Plan, Ethiopia Range/Livestock Consultancy
Anonymous 2000: Agro Ecological Zonation of Report prepared for the Government of the People’s
Ethiopia. Ministry of Agriculture, Addis Ababa, Ethiopia. Democratic Republic of Ethiopia. Technical Report,
http://www.fao.org/ag/AGP/AGPC/doc/counprof/ethiopia/ AG/ETH/82/010, 94 pp. Food and Agricultural
ethiopia.htm (January, 2011). Organization, Rome.
596 B. Haileselassie et al.
Food and Agricultural Organization (FAO) 1995: Country Lindsay WL, Norvell WA 1978: Development of DTPA soil test
Information Brief: Ethiopia Food and Agriculture for zinc, iron, manganese and copper. Soil Sci. Soc. Am. J.,
Organization of the United Nations. http://www.africa. 42, 421–428.
upenn.edu/eue_web/fao_soil.htm (December, 2010). Olsen SR, Cole CV, Watanabe FS, Deal LA 1954: Estimation of
Food and Agricultural Organization (FAO) 2000: Problem Soils Available Phosphorus in Soil by Extraction with Sodium
Database: Vertisols. http://www.fao.org/ag/agl/agll/prosoil/ Bicarbonate, pp 1—19, Government Printing Office,
vert.htm (December, 2010). Washington, DC. USDA Circular 939.
Food and Agricultural Organization (FAO) 2002: Web LocClim, Rupa TR, Tomar KP 1999: Zinc desorption kinetics as
Local Climate Monthly Estimator. http://www.fao.org/sd/ influenced by pH and phosphorus in soils. Comm. Soil
locclim/srv/locclim.home (December, 2010). Sci. Plant Anal., 30, 1951–1962.
Food and Agricultural Organization (FAO), Seyfu K. 1997: Tef. Eragrostis tef (Zucc.) Trotter. Promoting
Cooperazion-Italiana, IGAD 1998: The Soil and Terrain the Conservation and Use of Underutilized and Neglected
Database for Northeastern Africa. Crop Production Crops. 12, p. 35. Institute of Plant Genetic and Crop Plant
Systems Zones of IGAD Subregion. Land and Water Research, Gaterstleben/International Plant Genetic Res-
Digital Media Series 2. Food and Agricultural ources Institute, Rome. http://www.underutilized-species.
Organization, Rome. org/documents/PUBLICATIONS/tef.pdf (January, 2011).
Gao X, Schröder TJ, Hoffland E, Zou C, Zhang F, Van der Sharma BD, Mukhopadhyay SS, Katyal JC 2006: Distrbution
Zee SEATM 2010: Geochemical modeling of zinc bioavail- of total and DTPA zinc, copper, manganese, and iron in
ability for rice. Soil Sci. Soc. Am. J., 74, 301–309. vertisols of India. Comm. Soil Sci. Plant Anal.,
Gebremedhin B, Hirpa A, Kahsay B 2009: Feed Marketing in 37, 653–672.
Ethiopia. Results of Rapid Apprisal, 64 pp. International Syers JK, Nyamudeza P, Ahenkorah Y 2001: Sustainable
Livestock Research Institute, Addis Ababa. http:// nutrient management of vertisols. In The Sustainable
www.eap.gov.et/content/files/Documents/EAP Documents/ Managment of Vertisols, Eds JK Syers, FWT Penning de
Extension Development/newdoc/exten/Feed marketing in
Vries, P Nyamudeza, pp 43—70, CABI Publishing,
Ethiopia.pdf (January, 2011).
Wallingford.
Gebretsadikan H, Haile M, Yamoah CF 2009: Tillage
Tefera H, Belay G 2006: Eragrostis tef (Zuccagni) Trotter.
frequency, soil compaction and N-fertilizer rate effects on
[Internet] Record from Protabase. In: Brink M, Belay G
yield of teff (Eragrostis tef (Zucc) Trotter) in Central Zone
(eds) PROTA (Plant Resources of Tropical Africa/
of Tigray, North Ethiopia. Momona Eth. J. Sci., 1, 82–92.
Ressources végétales de l’Afrique tropicale), Wageningen.
Haque l, Lupwayi NZ, Tadesse T 2000: Soil micronutrient
http://database.prota.org/search.htm (December, 2010).
contents and relation to other soil properties in Ethiopia.
Teklu Y, Tefera H 2005: Genetic improvement in grain yield
Comm. Soil Sci. Plant Anal., 31, 2751–2762.
potential and associated agronomic traits of tef (Eragrostis
Hotz C, Brown KH 2001: Identifying population at risk of zinc
tef). Euphytica, 141, 247–254.
deficiency: the use of supplementation trails. Nutr. Rev.,
Tulema B, Zapta F, Aune JB, Sitaula B 2005: N fertilization, soil
59, 80–84.
type and cultivars effects on N use efficiency in tef
Itanna F 1996: Micronutrients status of three Ethiopia Vertisol
(Eragrostis tef (Zucc.) Trotter). Nutr. Cycling
landscapes at different agro ecological zones. In: The
Proceeding of Third Conference of the Ethiopian Soil Agroecosyst., 71, 203–211.
Science Society held in Addis Ababa, Ethiopia, 28—29 Umeta M, West CE, Fufa H 2005: Content of zinc, iron,
February 1996, pp. 153—161. Ethiopian Science and calcium and their absorption inhibitors in foods
Technology Commision, Addis Ababa. commonly consumed in Ethiopia. J. Food Comp. Anal.,
Jackson ML 1967: Soil Chemical Analysis, Prentice Hall of 18, 803–817.
India, New Delhi. Umeta M, West CE, Haidar J, Deurenberg P, Hautvast JGAJ
Jayne TS, Govereh J, Wanzala M, Demeke M 2003: Fertilizer 2000: Zinc supplementation and stunted infants in
market development: a comparative analysis of Ethiopia, Ethiopia: a randomozied controlled trail. Lancet,
Kenya and Zambia. Food Policy, 28, 293–316. 355, 2021–2026.
Khalili M, Lindgren E, Varvikko T 1993: A survey of mineral Umeta M, West CE, Haidar J, Hautvast JGAJ 2003: Factors
status of soils, feeds and cattle in the Selale Ethiopian associated with stuning in infants aged 5—11 months in the
highlands. II Trace elements. Trop. Anim. Health Prod, Dodota-Sire District, rural Ethiopia. J. Nutr.,
25, 193–201. 133, 1064–1069.